Mechanical brake for gun mounts



Aug. 15, 1950 F. c. EASTMAN MECHANICAL BRAKE FOR GUN MOUNTS 2Sheets-Sheet 1 Filed Jan. 14, 1948 Aug. 15, 1950 F. c. EASTMAN 2,513,531

MECHANICAL BRAKE FOR GUN MOUNTS Filed Jan. 14,1948 2 Sheets-Sheet 2fizz/an far F -ca' CIasi man Patented Aug. 15, 1950 UNITED STATES,earner OFFICE MECHANICAL BRAKE FOR GUN MOUNTS Fred C. Eastman,Marblehead, Mass, assignor to United Shoe Machinery Corporation,Flemington, N. 3., a corporation of New Jersey Application January 14,1948, Serial No. 2,316

4 Claims.

limited to preclude the firing of projectiles along particulartrajectories. Ordinarily the complex controls for swinging and laying agun barrel;

may be relied upon to determine its limits of movement, but thesusceptibility of such controls to disorder, especially during combatand in the instance of power driven gun mounts in airplanes, makes itessential that means be provided which shall positively prevent the:movement of a barrel beyond the desiredorpermissible extent. Animportant consideration in con.- nection with such means is that "thebraking power efiective to stop barrel movement at a predetermined limitshall not subject the gun to rebound or rocking movement that woulddelay or prevent firing accuracy.

An object of the invention is .to provide in a gun mount an improvedpositively acting brake for limiting travel of :gun whichshall besimple, inexpensive, light in weight, and compact in structure, andwhich shall, independently of mechanism driving said gun, operate in asmall confined space to quickly retard its motion with- 1 out efiectingreversal.

To this end a feature of the invention resides in the use of a series ofcontiguous wedge-like cams backed by shock-absorbing means and disposedwithin angular constraining walls to inter- .act frictionally on beingdisplaced by an element movable with the gun to be braked.

A further feature is in the arrangement of the parts whereby travel of agun in either of two opposite directions is resisted by the frictionalinterengagement of the cams as influenced by cushioning means, thelatter being represented herein as a spring.

These and other features of the invention will best be understood fromthe following description of a preferred embodiment considered inconnection with the accompanying drawings,

in which Fig. 1 is a view in side elevation .of a gun,

mounted to swing in azimuth and in elevation,

2 and in which the present invention has been embodied;

Fig. 2 is a deta l. on a larger scale, showing a sectional view of brakemounting, as indicated by the line II-II of Fig. 1;

Fig. 3 is an enlarged detail view of a gear segment with the brakingmechanism and other parts of the gun shown inFig. 1; and

Fig. 4 is an angular view drawn to a still larger scale and explcdedztoshow the parts comprising the braking mechanism.

While the description and drawings are here- .inafter directed toillustrating an application :of

the invention in limiting the movement :of a gun 1n elevation, it willbe understood that a similar arrangement may limit its movement inazimuth,

or in either of any two opposite directions.

The gun mount and its driving mechanism do not materially differ ingeneral arrangement from that disclosed in United :States Letters PatentNo. 2,391,956, granted to F. C. Eastman on January 1, 19%6, and entitledLimit Stop forGun Mounts. Since the details in this connection are of noparticular pertinence to the present invention, :a brief description ofthem will sumce. A gun It (Fig. 1) is supported for movement inelevation by being pivoted on its trunnions (not shown) in the sideframes ii? of a yoke or gun mount. The trunnion on the near sidesupports a segment gear Hi depending from and integral with an adapter16 arranged to rotate with the gun 45] in elevation .as will beunderstood. The yoke is completed by top and bottom cross supports (notshown), the top support being pivoted in a bearing 1!. to the supportingstructure in which the gun ismounted and the bottom support beingreceived in a bearing 29 secured to part of the structure in which thegun is mounted. The yoke is thus adapted to be turned about a verticalaxis so that the gun may be directed in-aziinuth. Elevation (anddepression) of the gun is effected by a pinion 22 which is driventhrough a gear train '(not .shown) by a motor 24 and which meshes withthe segment gear 14.

On the segment gear I i '(Figs. '1 .and 3) are fastened limit stops .26and 22 having rounded ends which may be .adjusta'bly spaced by adistance representing the permissible or desired limits of gun movementin elevation. The adjustment referred to 'is made by .affixing thesestops to gear segment It with dowel pins 30 :inserted in holes 32located equidistant from the turning axis of the trunnions.

Coming now more particularly. to the break-- ing mechanism, a flat,inverted L-shaped casing 34, best viewed in Figs. 3 and l, is secured toan inner portion of the near frame [2 and. preferably held relativelystationary by bolts 36. The casing 34, which may be of any angularconfiguration conveniently to accommodate available space, has an openside which is flush with the frame, its closed side being adjacent to,but separated from, the gear segment. The inner walls in each arm ofthis casing provide smooth and parallel bearing surfaces to support andconstrain for frictional interaction a series of close-fitting cams orwedge-like blocks. Preferably, both the casing 34 and these blocks areof hardened tool steel. The first of the series is a double-endedbumperblock 38 projecting horizontally from bearing slots 49 in the lowerextremity of the casing walls. The block 38 is positioned to convergewith the arcuate path of stops 26 and 28 so as to be engageabletherewith, and is provided in its upper surface with a central,widthwise extending notch having its acting faces 42 inclinedsubstantially at right angles to each other. Fitted to slide within thecasing 34 for frictionalaction with its Walls is a second wedge-likeblock 44 which has its tapering sides 46 truncated and equally beveledso as to be fully seated in the notch and evenly bear on both faces 42when the bumper block 38 is in its initial position and not displaced bycontact with either of the stops 26, 28. The holes 48 in the severalblocks have no function other than to decrease the overall weight of theassemblage without adversely affecting its structural strength.

Between projections 50 (see Figs. 3 and 4) of the upper side of theblock 44 is a horizontal recess 52 in which two cylindrical rollers 54may shift laterally for purposes hereinafter to be described. E'achroller 54 has a lug engaging a spring 56 that yieldingly separates therollers and normally holds them parallel with and adjacent to theprojections 59. The diameter of the.

rollers 54 exceeds the depth of the recess 52 by a very small amount sothat they serve to space from the block 44, and make line contacts with,a confronting wedge-like block 58 which is next in the series.

The block 58 resting on the rollers 54 is fitted to slide up and down infrictional contact with the upwardly extending walls of casing 34 andhas a face 60 beveled so as to bear on a correspondingly bevelled end 62of an adjoining block 8d. The block 64 extends horizontally in the otherarm of the casing 34. The extent to which the block 58 may be displacedupwardly in the casing is less than the depth of the aforementionednotch so that the contiguity of the blocks 58 and 64 is maintained asthe one slides at right angles relatively to the other. An end 66 of thehorizontally movable block 54 is contiguous with an inclined face of aspring-backed plunger 68 that projects into the casing and is the lastin the series of blocks. The bevel of end 66 is equal to that of theadjacent plunger face and disposed to convert its rubbing movement intodisplacement of the plunger 68 in directions at right angles toward andfrom the casing 34.

A loaded spring it engaging the plunger 63 is compressed in acylindrical housing 12 bolted to the casing 34. The limit of outwardyielding movement of the plunger 68 is determined by a stem 14 threadedin the housing 12 to engage the spring 'Hl.

' spring 10.

In operation of the driving mechanism to lay the gun in elevation, itwill be seen that as the desired or permissible extent of its movementis about to be reached, the segment gear l4 will have been swung so thatone of the limiting stops 26 or 28, movable with the segment ear, willcontact the bumper block 38. Further elevation (or depression) causesthe stop to displace in casing 34 the notched bumper block 33 to theleft (or right) and away from its inoperative position, and it will'inturn consecutively displace by frictional interaction each of thesuccessive blocks in the series. Movement of the bumper 38 away from itscentral and inoperative position (shown in Figs. 1 and 3) results in aface .42 rubbing on the corresponding side 56 so that block 44 isdisplaced. The force exerted by the block 38 acts diagonally on theblock 44 so that an entire vertical side of the latter rubs with nearlyuniform pressure upon the casing wall. Theblocks 44 and 58 operate inunison,

but if they were combined into an integral memher, it is probable insome installations that'the force acting on it would set up a couplingmovement such that a pair of diagonally opposite and reduced portions ofits sides would be subjected to excessive, even destructive, pressureslocking the member against movement relatively to the casing. In orderto obtain a broadly distributed frictional resistance along the verticalsides and avoid the possibility of cramping action, it is preferablethat the block 58 be permitted to shift laterally a small amount uponthe interposed rollers 54 during displacement of the blocks.

When the block 64 is moved by the pressure and interaction of the face60 on the end 62, block 64 likewise sustains a friction load thatresists movement along the horizontal walls of casing 34, and its otherend t6 slides relatively to the complementary bevelled plunger 58 todisplace the latter onl to the extent yieldingly permitted by the Thecompression with which the spring '50 resiliently acts to absorb andcushion the impact of the displaced plunger may be suitably variedbyturning the stem 14. It is to be noted that the ultimate energypotentially stored in the spring in will have been very considerablyreduced from that of the thrust of the limiting stop 26 or 28 on theblock 38, the diiference in energy having been frictionally spent by theblocks and casing 34. The braking power of such friction and springcompression accumulates quickly to render the motor 24 ineffectiveand/or overcome the momentum of the moving mass. The greater the thrustof a stop on the bumper block, the greater will be the opposing forceset up by friction of the blocks with the casing 34, by friction betweencontiguous sliding blocks, and by compression of spring Hi.

The position beyond which no further elevation (or depression) of thegun It may be effected is predetermined by the limits of displacementallowed the blocks and a corresponding limit of compression in thespring it. When the mass to be stopped is not moved with suificientenergy to cause these limits of displacement and compression to be quitereached, its motion will be stopped by the spring compression and theretarding friction which, as will now appear, likewise prevents backlashor rocking movements. During braking and while motion is only in thedirection of displacement of the wedge-like blocks, the energy of themass being braked that is not spent in friction will be absorbed incomif no energy were dissipated in friction during 4 brakingdisplacements of the blocks would it be possible for the spring Ill toreceive and discharge energy adequate to reverse the direction of theirdisplacement.

The amount of displacement in the blocks and the reacting force in thespring 10 tending to overcome and reverse such displacement depend onthe degree of bevel in the frictionally interacting faces of the blocks.Having each of them bevelled 45 provides displacements in the blockswhich are respectively equal to that of the spring 10. While otherbevels, and fewer or more blocks of different contour, may be employedin some applications to meet braking requirements, 45 bevels aregenerally preferred since they make for ease of construction, usuallyaid in fully utilizing installation space available for the brake, andprovide an advantageous combination in the factors of frictionalresistance and extent of braking displacement. With lesser bevels on theacting faces, it will be understood, the smaller and easierdisplacements necessitate a stiffer spring 10, or one having aninitially greater load, if the same braking power is to be elfected.Conversely, with bevels greater than 45 for the acting faces, largerdisplacements affording greater frictional resistance would permit thespring 10 to provide a smaller reacting force.

In many installations of the braking mechanism it may prove impracticalto confine the wedge-like cams within bearing Walls of a casing, andindeed it may be advantageous to use a casing of other configuration,such as one that is T-shaped or W-shaped, or to substitute a pluralityof bearing surfaces which are not even interconnected for suitablyconstraining cam displacements. An obvious advantage afforded by thecasing, however, is that it excludes dirt and lubricants which mightadversely affect the uniform friction desired along the bearingsurfaces.

Within a very few degrees of segment gear turning after the stop 26 or28 has contacted the bumper block 38, the further laying of the gun willhave been stopped, and the forces being in equilibrium, only a smallexternal force need be supplied by the motor 24 or otherwise to returnthe parts of the braking mechanism quickly to their initial positions.It will be clear that operation would not differ if the stops 26, 28were to remain stationary and the casing 34 swung with the bumper block38 upon gun movement to effect engagement with the stops; such anarrangement might prove a convenient alternative in a gun mount.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a gun mount having a frame element and a reversibly movablesegmental element for swinging a gun supported on said frame element,mechanism for limiting the travel of said segmental element in eitherdirection including a pair of spaced stops carried by one of saidelements and an intermediate braking mechanism associated with the otherof said elements, said braking mechanism comprising a double-endedbumper block displaceable in either of two opposite directions onengagement by one or the other of said stops, yieldable means foropposing such movement of the bumper block, said lastnamed meansincluding a series of frictionally interacting wedge-like cams one ofwhich bears on the face of a V-shaped notch in said bumper block andanother of which is backed by a resilient member, and walls forconstraining the series of cams to displacements against the resistanceof said resilient member.

2. Mechanism as set forth in claim 1 further characterized in thatconfronting cams of the series tending to bind against said walls haveinterposed between their confronting cam faces means for relieving thebinding pressure.

3. Mechanism as set forth in claim 2 further characterized in that thepressure relieving means comprises rollers having line contacts withsaid confronting cams.

4. In a gun mount having a frame element and a segmental elementreversibly movable with the gun, mechanism for limiting the travel ofsaid segmental element in either direction including a pair of spacedstops carried by one of said elements and an intermediate brakingmechanism associated with the other of said elements comprising anangular casing confining a doubleended block provided with a V-shapednotch, said block being displaceable relatively to the casing onengagement by one or the other of said stops, and yieldable meansconstrained within the easing including resiliently movable means and aseries of frictionally interacting wedge-like cams for opposing movementof the bumper block by bearing on a face of its V-shaped notch.

FRED C. EASTMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,123,853 Courson Jan. 5, 19151,263,374 Christy Apr. 23, 1918 1,410,436 White Mar. 21, 1922 1,561,713Gorton Nov. 17, 1925 1,673,507 Haseltine June 12, 1928 1,826,837Stebbins Oct. 13, 1931 1,875,096 Miller Aug. 30, 1932 2,372,096 Lessmanet al Mar. 20, 1945 2,391,956 Eastman Jan. 1, 1946

